Mold, Moisture, and Your Home
Mold Basics
The key to mold control is moisture control.
-
If mold is a problem in your home, you should clean up the
mold promptly and fix the water problem.
-
It is important to dry water-damaged areas and items within
24-48 hours to prevent mold growth.
Why is mold growing in my home?
Molds are part of the natural environment. Outdoors, molds play
a part in nature by breaking down dead organic matter such as
fallen leaves and dead trees, but indoors, mold growth should be
avoided. Molds reproduce by means of tiny spores; the spores are
invisible to the naked eye and float through outdoor and indoor
air. Mold may begin growing indoors when mold spores land on
surfaces that are wet. There are many types of mold, and none of
them will grow without water or moisture.
Can mold cause health problems?
Molds are usually not a problem indoors, unless mold spores land
on a wet or damp spot and begin growing. Molds have the
potential to cause health problems. Molds produce allergens
(substances that can cause allergic reactions), irritants, and
in some cases, potentially toxic substances (mycotoxins).
Inhaling or touching mold or mold spores may cause allergic
reactions in sensitive individuals. Allergic responses include
hay fever-type symptoms, such as sneezing, runny nose, red eyes,
and skin rash (dermatitis). Allergic reactions to mold are
common. They can be immediate or delayed. Molds can also cause
asthma attacks in people with asthma who are allergic to mold.
In addition, mold exposure can irritate the eyes, skin, nose,
throat, and lungs of both mold-allergic and non-allergic people.
Symptoms other than the allergic and irritant types are not
commonly reported as a result of inhaling mold. Research on mold
and health effects is ongoing. This brochure provides a brief
overview; it does not describe all potential health effects
related to mold exposure. For more detailed information consult
a health professional. You may also wish to consult your state
or local health department.
How do I get rid of mold?
It is impossible to get rid of all mold and mold
spores indoors; some mold spores will be found floating through
the air and in house dust. The mold spores will not grow if
moisture is not present. Indoor mold growth can and should be
prevented or controlled by controlling moisture indoors. If
there is mold growth in your home, you must clean up the mold
and fix the water problem. If you clean up the mold, but don't
fix the water problem, then, most likely, the mold problem will
come back.
Who Should do the Cleanup?
Who should do the cleanup depends on a number of factors. One
consideration is the size of the mold problem. If the moldy area
is less than about 10 square feet (less than roughly a 3 ft. by
3 ft. patch), in most cases, you can handle the job yourself,
following the guidelines below.
-
If there has been a lot of water damage, and/or mold growth
covers more than 10 square feet, consult the U.S.
Environmental Protection Agency (EPA) guide: Mold
Remediation in Schools and Commercial Buildings. Although
focused on schools and commercial buildings, this document
is applicable to other building types. It is available free
by calling the EPA Indoor Air Quality Information
Clearinghouse at (800) 438-4318.
-
If you choose to hire a contractor (or other professional
service provider) to do the cleanup, make sure the
contractor has experience cleaning up mold. Check references
and ask the contractor to follow the recommendations of the
EPA, the guidelines of the American Conference of
Governmental Industrial Hygenists (ACGIH), or other
guidelines from professional or government organizations.
-
If you suspect that the
heating/ventilation/air conditioning (HVAC) system may be
contaminated with mold (it is part of an identified moisture
problem, for instance, or there is mold near the intake to
the system), consult EPA's guide Should You Have the Air
Ducts in Your Home Cleaned?before taking further action. Do
not run the HVAC system if you know or suspect that it is
contaminated with mold - it could spread mold throughout the
building. Call (800) 438-4318 for a free copy.
-
If the water and/or mold damage was caused by sewage or
other contaminated water, then call in a professional who
has experience cleaning and fixing buildings damaged by
contaminated water.
-
If you have health concerns, consult a health professional
before starting cleanup.
Tips and Techniques
The tips and techniques presented in this section will help you
clean up your mold problem. Professional cleaners or remediators
may use methods not covered in this publication. Please note
that mold may cause staining and cosmetic damage. It may not be
possible to clean an item so that its original appearance is
restored.
-
Fix plumbing leaks and other water problems
as soon as possible. Dry all items completely.
-
Scrub mold off hard surfaces with detergent and water, and
dry completely.
-
Absorbent or porous materials, such as ceiling tiles and
carpet, may have to be thrown away if they become moldy.
Mold can grow on or fill in the empty spaces and crevices of
porous materials, so the mold may be difficult or impossible
to remove completely.
-
Avoid exposing yourself or others to mold.
-
Do not paint or caulk moldy surfaces. Clean up the mold and
dry the surfaces before painting. Paint applied over moldy
surfaces is likely to peel.
-
If you are unsure about how to clean an item, or if the item
is expensive or of sentimental value, you may wish to
consult a specialist. Specialists in furniture repair,
restoration, painting, art restoration and conservation,
carpet and rug cleaning, water damage, and fire or water
restoration are commonly listed in phone books. Be sure to
ask for and check references. Look for specialists who are
affiliated with professional organizations.
What to Wear when Cleaning Moldy Areas
-
Avoid breathing in mold or mold spores. In
order to limit your exposure to airborne mold, you may want
to wear an N-95 respirator, available at many hardware
stores and from companies that advertise on the Internet.
(They cost about $12 to $25.) Some N-95 respirators resemble
a paper dust mask with a nozzle on the front, others are
made primarily of plastic or rubber and have removable
cartridges that trap most of the mold spores from entering.
In order to be effective, the respirator or mask must fit
properly, so carefully follow the instructions supplied with
the respirator. Please note that the Occupational Safety and
Health Administration (OSHA) requires that respirators fit
properly (fit testing) when used in an occupational setting;
consult OSHA for more information (800-321-OSHA).
-
Wear gloves. Long gloves that extend to the middle of
the forearm are recommended. When working with water and a
mild detergent, ordinary household rubber gloves may be
used. If you are using a disinfectant, a biocide such as
chlorine bleach, or a strong cleaning solution, you should
select gloves made from natural rubber, neoprene, nitrile,
polyurethane, or PVC. Avoid touching mold or moldy items
with your bare hands.
-
Wear goggles. To avoid getting mold or mold spores in
your eyes, safety goggles that do not have ventilation holes
are recommended.
How Do I Know When the Remediation or Cleanup is Finished?
You must have completely fixed the water or moisture problem
before the cleanup or remediation can be considered finished.
-
You should have completed mold removal. Visible mold and
moldy odors should not be present. Please note that mold may
cause staining and cosmetic damage.
-
You should have revisited the site(s) shortly after cleanup
and it should show no signs of water damage or mold growth.
-
People should have been able to occupy or re-occupy the area
without health complaints or physical symptoms.
-
Ultimately, this is a judgment call; there is no easy
answer. If you have concerns or questions call the EPA
Indoor Air Quality Information Clearinghouse IAQ INFO at
(800) 438-4318.
Moisture and Mold Prevention and Control Tips
-
Moisture control is the key to mold control, so when water
leaks or spills occur indoors - ACT QUICKLY. If wet or damp
materials or areas are dried 24-48 hours after a leak or
spill happens, in most cases mold will not grow.
-
Clean and repair roof gutters regularly.
-
Make sure the ground slopes away from the building
foundation, so that water does not enter or collect around
the foundation.
-
Keep air conditioning drip pans clean and the drain lines
unobstructed and flowing properly.
-
Keep indoor humidity low. If possible, keep indoor humidity
below 60 percent (ideally between 30 and 50 percent)
relative humidity. Relative humidity can be measured with a
moisture or humidity meter, a small, inexpensive ($10-$50)
instrument available at many hardware stores.
-
If you see condensation or moisture collecting on windows,
walls or pipes ACT QUICKLY to dry the wet surface and reduce
the moisture/water source. Condensation can be a sign of
high humidity.
Actions that will help to reduce humidity:
-
Vent appliances that produce moisture, such
as clothes dryers, stoves, and kerosene heaters to the
outside where possible. (Combustion appliances such as
stoves and kerosene heaters produce water vapor and will
increase the humidity unless vented to the outside.)
-
Use air conditioners and/or de-humidifiers when needed.
-
Run the bathroom fan or open the window when showering. Use
exhaust fans or open windows whenever cooking, running the
dishwasher or washing dishes, etc.
-
Actions that will help prevent condensation:
-
Reduce the humidity (see above).
-
Increase ventilation or air movement by opening doors and/or
windows, when practical. Use fans as needed.
-
Cover cold surfaces, such as cold water pipes, with
insulation.
-
Increase air temperature.
Testing or Sampling for Mold
Is sampling for mold needed? In most cases, if
visible mold growth is present, sampling is unnecessary. Since
no EPA or other federal limits have been set for mold or mold
spores, sampling cannot be used to check a building's compliance
with federal mold standards. Surface sampling may be useful to
determine if an area has been adequately cleaned or remediated.
Sampling for mold should be conducted by professionals who have
specific experience in designing mold sampling protocols,
sampling methods, and interpreting results. Sample analysis
should follow analytical methods recommended by the American
Industrial Hygiene Association (AIHA), the American Conference
of Governmental Industrial Hygienists (ACGIH), or other
professional organizations.
Suspicion of hidden mold
You may suspect hidden mold if a building smells moldy, but you
cannot see the source, or if you know there has been water
damage and residents are reporting health problems. Mold may be
hidden in places such as the back side of dry wall, wallpaper,
or paneling, the top side of ceiling tiles, the underside of
carpets and pads, etc. Other possible locations of hidden mold
include areas inside walls around pipes (with leaking or
condensing pipes), the surface of walls behind furniture (where
condensation forms), inside ductwork, and in roof materials
above ceiling tiles (due to roof leaks or insufficient
insulation).
Investigating hidden mold problems
Investigating hidden mold problems may be
difficult and will require caution when the investigation
involves disturbing potential sites of mold growth. For example,
removal of wallpaper can lead to a massive release of spores if
there is mold growing on the underside of the paper. If you
believe that you may have a hidden mold problem, consider hiring
an experienced professional.
Cleanup and Biocides
Biocides are substances that can destroy living organisms. The
use of a chemical or biocide that kills organisms such as mold
(chlorine bleach, for example) is not recommended as a routine
practice during mold cleanup. There may be instances, however,
when professional judgment may indicate its use (for example,
when immune-compromised individuals are present). In most cases,
it is not possible or desirable to sterilize an area; a
background level of mold spores will remain - these spores will
not grow if the moisture problem has been resolved. If you
choose to use disinfectants or biocides, always ventilate the
area and exhaust the air to the outdoors. Never mix chlorine
bleach solution with other cleaning solutions or detergents that
contain ammonia because toxic fumes could be produced.
Please note: Dead mold may still cause allergic reactions
in some people, so it is not enough to simply kill the mold, it
must also be removed.